Comparing Means Flashcards
What is the most commonly used statistical technique to compare 2 means?
t-Test
In order to use a t-Test the data must be _____.
Parametric (Interval or Ratio)
What is the purpose of a t-Test?
To determine if there is a difference between 2 groups
What does the difference between group means indicate?
That the degree of separation between group (effect size)
Comparing means is based on the relationship between what two sample characteristics?
Mean and Variance
_____ and _____ will describe the extent of the treatment effect
Mean
Variance
What does the variance tell us?
how variable the scores are within each group
What is Standard Error of the Mean?
a method used to estimate the standard deviation of a sampling distribution
In other words, it tells us how the mean varies with different experiments measuring the same quantity
How do you calculate the standard error of the mean?
(σM)= σ / √N
What happens to the standard error of the mean as population size increases?
Decreases
This is expected because if the mean at each step is calculated using a lot of data points, then a small deviation in one value will cause less effect on the final mean
Given σM how do we calculate our t-score?
t = (mean of the sample - mean of the population) / standard error of the mean
So now that we have our calculated t-value what do we do?
Compare it to the table t-value
We can reject the null hypothesis when our calculated t-value is _____ the table (critical) value
Greater than (>)
What are the 2 types of t-tests?
Paired or Unpaired
Both types of t-tests assume what?
that the data is from a normal distribution
